This invention relates to an apparatus and method for milling the end surfaces of textile packages, and is particularly useful in grinding away the sharp edges formed on the base end of paper textile cones and tubes in order to prevent yarn tail breakage during yam winding. Winding takes place in open-end spinning, ring spinning, twisting and other processes wherein yarn is wound onto the yarn packages. Yarn packages used in these processes are wound with a trailing xe2x80x9ctailxe2x80x9d of yarn by which the end of yarn on an exhausted package is tied to the leading end of yarn on the succeeding full package. The tail is necessary if the transfer from the exhausted to a full package is to take place without dropping needles, which causes a serious defect in the knitted fabric.
While the invention disclosed in this application has utility on a number of different types of yarn packages, for purposes of illustration the invention will be described with reference to a tubular textile yarn package which is formed of pressed paper and has a generally frusto-conical shape. While packages come in various configurations, one common type of package is a cone which has an angle of taper of 5 degrees, 57 minutes.
As described above, this type of package must be wound with a tail in order for it to be considered a first quality package. An acceptable rate of yarn tail breakage is about one percent, with between two and three percent being average. Since knitters require yarn packages with yarn tails, yarn tail breakage is a serious problem both from the standpoint of yarn quality and from the standpoint of increased cost to the processor which results from backwinding defective packages, returns from customers, and the like.
The yarn tail is usually formed by taking a length of yarn and extending part of it over the open mouth of the large end of the package. The package is then applied to a cradle which has a package holder base plate which fits into the large end of the package and holds the yarn, and a package holder nose plate which secures the package for proper rotation about a fixed axis. See FIG. 12. The package is wound by surface drive against a rotating drum which feeds the yarn onto the rotating package in a predetermined pattern. This assembly is referred to generally herein as a xe2x80x9cyarn package holder.xe2x80x9d
Until relatively recently, winders were designed so that the package holder base plate had an internal taper which corresponded to the taper of the package. This meant that for a fairly substantial distance on the order of 6 mm, the surface of the package holder base plate and the inner surface of the package were parallel with each other and in flush contact. The yarn trapped across the mouth of the package was thereby held firmly along the entire length of contact between the package and the base plate. This resulted in a secure grip while, at the same time, any stress applied to the yarn was spread over a relatively long distance.
Some winder manufacturers have designed cradles which have universal package holder base plates and nose plates. The plates are adapted to receive packages having various angles of taper without the additional labor and lost operating time required to conform the cradle to the precise type of package being wound. While substantial efficiencies are achieved by this new type of winder, the angle of the portion of the base plate which fits into the large end of the package is no longer necessarily parallel to and flush with the inner surface of the package. Therefore, the yarn tail passes between the package and the base plate at two diametrically opposed edges rather than wide, flush surfaces. As long as there is little or no relative movement between the base plate and package, this fact is of little consequence. Therefore, when starting an empty package, there is often little difficulty since the package itself is very lightweight and has very little inertia.
Accordingly, the package begins rotation with the base plate and there is little or no relative movement which could cause the yarn to be pinched or cut. However, as yarn is wound onto the package, it increases substantially in weight and inertia. Many winders have automatic stop motions which utilize, for example, an air brake to very quickly stop the rotation of package when the package is full or when a break in the yarn occurs. The substantial inertia created by a full or near-full package is sufficient to cause the package to rotate relative to the base plate during stopping and starting. In the new types of winders described above, the edge of the base plate which presses against the yarn exerts a substantial amount of force and is more than sufficient to cut the yarn in two. As a result, the yarn package is no longer first quality and must either be rewound or sold as second quality.
Murata winders are widely used in the textile industry and present a unique, potential cause of yarn tail breaks. Murata winders include a rubber drive ring which sits on one end of the yarn package holder and, when the package is donned, sits against the adjacent end of the package. The drive ring contacts the driving surface of the drum during the initial winding phase and causes the package to rotate. When enough yarn has been built up on the package, the diameter of the package becomes greater than the diameter of the drive ring, and thus the package is thereafter rotated by direct contact between the package and the drum.
It has been observed that the rubber ring will sometimes cut the yarn tail both during starting and stopping due to the contact between the rubber ring and the end edge of the package across which the yarn tail extends. The problem has become progressively worse as the winding speed of modern winders, open-end spinning machines, twisters, and the like have increased.
Applicant has reduced this problem to a significant extent by modifying the design of the package to incorporate grooves into the end of the packages which protect the yarn by providing a slight recess in which the yarn at least partially resides thereby reducing the force on the yarn. This development is exemplified in applicant""s prior U.S. Pat. No. 4,700,904.
Paper textile packages have improved in quality in recent years by reducing manufacturing tolerances to provide packages with very little variation from package to package. This has resulted in precisely cut surfaces which leave sharp edges which can easily cut through a yarn as a result of even momentary contact. For example, the end of a paper cone thus has a very flat base with very sharp edges on the inner and outer sides. These edges must be xe2x80x9ceasedxe2x80x9d slightly in order to prevent loss of transfer tails, as described above. The invention disclosed in this application permits this to be done quickly, inexpensively and automatically during package manufacture by milling these sharp edges away without effecting the quality of the package. The milling takes place during a grinding process, and thus the term xe2x80x9cgrindingxe2x80x9d is used generically in this application to describe in general a process by which very sharp edges are eased to prevent yarn cutting. The grinding performs two functions. It removes the sharp edges and also leaves a slightly roughened, fuzzy surface caused by tearing loose paper fibers on the surface of the package. The rough surface provides a xe2x80x9cnestxe2x80x9d within which the yarn is positioned, protecting it from abrasion and breaking.
Therefore, it is an object of the invention to provide an apparatus and method for milling the end surfaces of textile packages which is particularly useful in grinding away the sharp edges formed on the base end of paper textile cones and tubes in order to prevent yarn tail breakage during yarn winding.
It is another object of the invention to provide a apparatus and method for milling the end surfaces of textile packages which grinds away sharp surfaces on the end, and inner and outer edges of the base of a textile package simultaneously.
It is another object of the invention to provide a apparatus and method for milling the end surfaces of textile packages which grinds away sharp surfaces on the end, and inner and outer edges of the base of a textile package automatically.
It is another object of the invention to provide a apparatus and method for milling the end surfaces of textile packages which grinds away sharp surfaces on the end, and inner and outer edges of the base of a textile package as an integral part of the package manufacturing process.
It is another object of the invention to provide a apparatus and method for milling the end surfaces of textile packages which grinds away sharp surfaces on the end, and inner and outer edges of the base of a textile package with precise uniformity from package to package in order to maintain the precise and uniform dimensions designed into the package.
These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing a grinding apparatus for grinding away sharp edges on an end of a textile package having an inner edge and a spaced-apart outer edge formed on the end of the package. The apparatus comprises a base, a first grinding element mounted on the base for movement relative to the textile package and having a grinding surface with an angle oblique to the inner edge of the textile package for being urged against the inner edge of the textile package and a second grinding element mounted on the base for movement relative to the textile package and having a grinding surface angle with an angle oblique to the outer edge of the textile package for being urged against the outer edge of the textile package.
According to one preferred embodiment of the invention, a third grinding element is mounted on the base for movement relative to the textile package and having a grinding surface for engaging and grinding the end of the textile package between the inner and outer edges.
According to another preferred embodiment of the invention, the grinding surfaces of the first, second and third grinding elements are positioned in an axially-extending plane for being simultaneously engaged by the outer edge, inner edge and end of the textile package.
According to another preferred embodiment of the invention, the base is mounted for rotation relative to a stationarily mounted textile package.
According to yet another preferred embodiment of the invention, the first and second grinding elements are pivotally mounted for movement away from the textile package as the textile package is urged against the first and second grinding elements.
According to yet another preferred embodiment of the invention, the first and second grinding elements are biased for being normally positioned into an interference position in relation to the respective inner and outer edges of the textile package.
According to yet another preferred embodiment of the invention, a grinding apparatus is provided for simultaneously grinding away sharp edges on a textile package having an inner edge and a spaced-apart outer edge formed on the end of the package. The apparatus includes a base mounted for rotation relative to a textile package and a plurality of first biased grinding elements mounted on the base in spaced-apart relation for movement relative to the textile package. Each of said first grinding elements has a grinding surface with an angle oblique to the inner edge of the textile package for being urged against the inner edge of the textile package. A plurality of second biased grinding elements are mounted on the base in spaced-apart relation for movement relative to the textile package, each of said second grinding elements having a grinding surface with an angle oblique to the inner edge of the textile package for being urged against the inner edge of the textile package. A plurality of third grinding elements are mounted on the base for movement relative to the textile package and have a grinding surface for engaging and grinding the end of the textile package. The first, second and third grinding elements have a grinding surface in an axially-extending plane for being simultaneously engaged by the outer edge, inner edge and end of the textile package.
According to yet another preferred embodiment of the invention, the plurality of first grinding elements and the plurality of second grinding elements are positioned in alternating spaced-apart relation to each other around the periphery of the base.
According to yet another preferred embodiment of the invention, the plurality of first grinding elements and said plurality of second grinding elements are positioned in alternating spaced-apart relation to each other in an arcuate pattern.
According to yet another preferred embodiment of the invention, the plurality of third grinding elements each includes a grinding surface defining a plane parallel to a plane defined by the end of the textile package for grinding away the end of the textile package without changing the plane of the end of the package.
According to yet another preferred embodiment of the invention, the plurality of third grinding elements each includes a stationary grinding surface defining a plane parallel to a plane defined by the end of the textile package, said third grinding elements comprising a stop restricting axial movement of the textile package against the grinding elements past a predetermined distance.
According to yet another preferred embodiment of the invention, each of said first grinding elements comprises at least one upwardly tapering grinding surface for engaging a respective surface of the textile package.
According to yet another preferred embodiment of the invention, each of said first and second grinding elements includes upwardly extending and opposed first and second grinding surfaces mounted for being repositioned to expose a second grinding surface to the textile package upon wear of the first grinding surface.
An embodiment of the method of grinding away sharp edges of a textile package having an inner edge and a spaced-apart outer edge formed on the end of the package according to the invention comprises the steps of holding the package, moving the package axially against a rotating base having thereon a first grinding element for movement relative to the textile package and having a grinding surface with an angle oblique to the inner edge of the textile package for being urged against the inner edge of the textile package, a second grinding element for movement relative to the textile package and having a grinding surface angle with an angle oblique to the outer edge of the textile package for being urged against the outer edge of the textile package. The package is removed from contact with the first and second grinding elements after the sharp edges have been removed.
According to one preferred embodiment of the invention, the method includes the step of moving the package axially against a rotating base having thereon a third grinding element for movement relative to the textile package and having a grinding surface for engaging and grinding the end of the textile package.
According to another preferred embodiment of the invention, the method includes the step of moving the textile package against a rotating base wherein the grinding steps take place simultaneously.
According to yet another preferred method according to an embodiment of the invention, a method of grinding away sharp edges on a textile package having an inner edge and a spaced-apart outer edge formed on the end of the package is provided and comprises the steps of holding the package and moving the package axially against a rotating base having thereon a plurality of first biased grinding elements mounted in spaced-apart relation for movement relative to the textile package. Each of said first grinding elements has a grinding surface with an angle oblique to the inner edge of the textile package for being urged against the inner edge of the textile package. A plurality of second biased grinding elements are mounted in spaced-apart relation for movement relative to the textile package, each of said second grinding elements having a grinding surface with an angle oblique to the inner edge of the textile package for being urged against the inner edge of the textile package. A plurality of third grinding elements are mounted on the base for movement relative to the textile package and have a grinding surface for engaging and grinding the end of the textile package. The first, second and third grinding elements have a grinding surface in an axially-extending plane for being simultaneously engaged by the outer edge, inner edge and end of the textile package. The textile package is allowed to contact the first, second and third grinding elements for a sufficient amount of time to grind away the sharp edges of the textile package, and then the package is removed from contact with the grinding surfaces.